1. Field of Invention
The present invention relates to an umbilical member treatment device of an industrial robot. In particular, the present invention relates to an umbilical member treatment device which is used at the wrist part of an industrial robot etc.
2. Description of Related Art
The front end of the wrist part of an industrial robot is provided with a welding gun or hand. To drive these welding gun or hand, it is necessary to lay a lot of umbilical members, such as cables which supply power or signals, or tubes which feed cooling water or drive air, up to the wrist part etc. of the robot.
The wrist part of an industrial robot includes a first engaging member and a second engaging member which are engaged with each other and which rotate relative to each other about a predetermined rotational axis. Japanese Patent Publication No. 2001-353684 A1 Japanese Patent Publication No. 08-197482 A1, and Japanese Utility Model Registration No. 2553843 disclose configurations in which one of the first engaging member and second engaging member is additionally provided with a pipe member which extends along the rotational axis. Further, the first engaging member and the second engaging member are provided with umbilical member fastening parts which fasten the plurality of umbilical members. The plurality of umbilical members pass through the hollow part of the pipe member in the longitudinal direction and are fastened by respective umbilical member fastening parts to the first engaging member and the second engaging member.
Furthermore, Japanese Patent No. 3830488 discloses a configuration which is provided with a mutually concentrically arranged inside pipe member and outside pipe member. In this case, the plurality of umbilical members are divided into two groups. One group is passed through the inside of the inside pipe member, while the other group is passed between the inside pipe member and the outside pipe member. Therefore, the groups of umbilical members can be kept from being twisted or rubbing against each other and the lifetime of the umbilical members can be extended.
However, the above-mentioned prior art has the following defects.
First, if merely extending a plurality of umbilical members along the rotational axis in the longitudinal direction, absorption of twisting requires that a sufficient distance in the direction of the rotational axis be secured. Further, to keep umbilical members from contacting the pipe member, the diameter of the pipe member also should be made sufficiently large for the plurality of umbilical members. However, in particular, at the front end of the wrist part of an industrial robot, securing sufficient space is difficult.
Furthermore, when employing an inside pipe member and an outside pipe member, the structure becomes complicated and a larger space compared with when requiring a single pipe member. As explained above, securing such a large space is difficult at the front end of the wrist part of an industrial robot.
The present invention was made in consideration of such a situation and has as its object the provision of an umbilical member treatment device which is used at the wrist part of a robot etc. and which is simpler and smaller in size than the prior art.